1. Field of the Invention
The present invention relates to surgical instruments. More particularly, the invention relates to handles for endoscopic or laparoscopic surgical instruments having a novel locking mechanism disposed within the handle to provide for positioning and locking of a tool member of the instrument.
2. Discussion Of the Related Art
Endoscopic surgical procedures are procedures performed in any hollow viscus of the body through narrow endoscopic tubes which are inserted through small entrance wounds in the skin. Laparoscopic surgical procedures are endoscopic procedures in which surgery is performed in the abdominal cavity through small incisions. Endoscopic and laparoscopic procedures generally require that any instrumentation inserted into the body be sealed, i.e., provisions must be made to ensure that gases, used to insufflate the surgical region, do not exit the body through the endoscopic or laparoscopic incision or instrument. Moreover, endoscopic and laparoscopic procedures often require the surgeon to act on organs, tissues and vessels far removed from the incision, thereby requiring that any instruments be used in such procedures be long and narrow while being functionally controllable from one end of the instrument, i.e., the proximal end. For purposes of clarity, the remainder of the following discussion will refer to endoscopic procedures and instruments used therefor. It is to be understood, however, that the present invention is also meant to be applicable in laparoscopic procedures as well as any other applicable procedure requiring precision control and/or locking of a tool mechanism.
Various endoscopic surgical instruments which utilize generally complex tool and jaw actuating mechanisms in order to facilitate use of the devices at a surgical site exist in the art. Many such devices provide an intricate construction in which a linkage mechanism for opening and closing the tool mechanism or jaws requires numerous moving parts, while a sliding arrangement is provided between two extended rod members to activate the linkage mechanism in response to movement of the handle members. It is often necessary in many of these devices for the surgeon, or an assistant, to maintain a constant force on the handles in order to keep the tool or jaw mechanism closed. This is particularly true for instruments such as grasping or gripping devices including forceps, needle holders, or retractors. Constraints such as these limit the surgeon's flexibility and often require additional personnel to be present in the operating room to assist in handling the instruments, thus restricting movement in an already confined location.
To alleviate the above problem, attempts have been made to provide locking mechanisms on the handles of the surgical instruments which allow surgeons to lock and/or clamp the jaw members in place. These locking mechanisms allow the surgeon or the surgical assistant to use their hands for other more necessary functions. Typically such locking devices include arm members which extend between scissor-type handles so that a series of ridges or ribs on each arm member engage corresponding ridges on the opposite arm to lock the handles in position. Bending one arm in relation to the other releases the locking mechanism.
One disadvantage associated with these devices concerns the release of the locking mechanism for subsequent movement of the jaw members to remove or reposition the instrument. Generally, the arm members of locking mechanisms are constructed of a resilient material, such as stainless steel or rigid plastic, and the locking forces which hold the arm members in engagement are generated by the natural flexing and biasing of the material from which the arm members are constructed. To release the locking mechanism, the arms must be disengaged by overcoming the locking forces of the arms. Typically, this is accomplished by manually flexing the arms away from each other, necessitating the use of two hands, one to grasp the instrument, and the other to forcibly move the arm members.
Another disadvantage with locking mechanisms located on the handles is that they require special care in sterilization, packaging and storage, as well as in normal handling in the operation room. Dirt and debris may clog the fibs of the locking mechanism thus reducing its effectiveness, and damage to the fibs during storage or packaging may disable the fibs, rendering the locking mechanism useless.
U.S. Pat. No. 1,452,373, to Gomez discloses a typical locking mechanism for a surgical instrument in which a plurality of ribs are provided on an extension of the handle member which engage a similar rib member on the opposite handle. Once engaged, the handles must be moved away from each other perpendicular to their longitudinal axis to disengage the locking mechanism to release the jaw mechanism.
U.S. Pat. No. 4,896,661, to Bogert et al. discloses a surgical instrument having a ratchet mechanism positioned on the handle members which includes a curved rack member attached to one handle member which passes through a slot in the other handle member. A releasable pawl member is provided on the second handle to engage the rack member and provide a means for releasing the ratchet.
U.S. Pat. No. 4,935,027, to Yoon discloses a surgical instrument having a ratchet mechanism positioned between the handle members. A rack member is provided which extends from one handle and passes through a slot in the second handle to lock the handles in place. Pivoting the rack member away from corresponding grooves in the slot will release the ratchet mechanism.
U.S. Pat. No. 4,428,374, to Auburn discloses a surgical instrument having means for positioning and holding the handle members in relation to each other. A rack member is provided on one handle member which extends through a slot in the second handle member in which a releasable pawl mechanism is provided to engage and disengage the rack member.
The novel surgical instrument according to the present invention obviates the disadvantages encountered in the prior an and provides a precise instrument which is easy to manufacture and efficient to use. The present invention eliminates the need for an external locking device and provides for operation and manipulation of the surgical instrument by a single hand and for locking and unlocking the instrument. The novel surgical instrument further enables a surgeon to actuate the locking mechanism from multiple locations on the handle. The instrument locking mechanism of the present invention incorporates many features which are of use to the surgeon during an operation, including a single jaw control mechanism for effecting both jaw closure and locking while maintaining a lightweight construction in an easy to control device in which all of the features may be operated with one hand. Furthermore, the features are positioned so as to provide a maximum line of sight for the surgeon without obstructing the view to the surgical site.